The present invention relates to a method and device for controlling a central locking system (CLS) for door locks and hinged lid locks of a motor vehicle that has multiple station operation of the CLS from a first mechanical locking station on a trunk lid and at least one further mechanical locking station on a door. The multiple station operation is performed via a first electrical control switch assigned to the first locking station and at least a second electrical control switch which is assigned to the further locking station, each of the first and second electrical control switches being switchable via the assigned locking station for the generation of unlocking and locking control signals which bring about a corresponding activation of the CLS. The first locking station is movable into a key-secured position by actuation via a key in a locking direction starting from an unlocked position or a neutral key withdrawal position to cause the generation of a locking control signal of the first control switch, which is also actuated when the first locking station is moved into the key-secured position, from which key-secured position the associated lock can only be unlocked again by the key and not by the CLS, the actuation of the first locking station in the locking direction being directed, with respect to the neutral key withdrawal position, in the opposite direction to an actuation of the first locking station in the unlocking direction.
Central locking systems of the above type are known by installation in vehicles manufactured by Mercedes-Benz. "Centrally locking" means locking the multiple locking stations of a vehicle from a single location. The known central locking system offers the advantage to the vehicle user that the lock of the trunk lid, which can be opened from outside without using a key when the lock is unlocked, can be mechanically locked and then remain locked even when the door locks have been unlocked centrally. This is achieved in that the vehicle user turns the lock cylinder on the trunk lid in the locking direction and withdraws the key in a securing position of the lock cylinder (which is always designated below as "key-secured position") which deviates from the neutral key withdrawal position. This possibility is referred to in the operating instructions of the correspondingly equipped vehicles. In German Patent Document DE 35 31 349 C1 also, reference is made to the mechanical lockability of the lock of the trunk lid and its uncoupling from the function of the central locking system brought about thereby in connection with the discussion of the prior art.
However, this undoubtedly desirable securing option can in certain cases reduce the operating convenience of the vehicle due to the central locking which can be controlled at least from the driver's door and the trunk lid via their locking station or lock cylinders. Such a situation arises when the vehicle user wishes to put something in the trunk before starting a journey and, for this purpose, centrally unlocks the vehicle from its locking station. If, after closing the trunk lid, he wishes to lock it with the key in the manner described above, the central locking system is also unavoidably activated in the locking direction via the control switch assigned to the locking station. The vehicle user then finds a locked driver's door and has to unlock it again before getting in and beginning the journey, the other door locks also being centrally unlocked. The trunk lid then remains locked as desired and the contents of the trunk are then protected from unauthorized access even when the door locks are centrally unlocked from the driver's door.
A keyless remote-controllable central locking system (German Patent Document DE 33 13 092 C2), the hand-held transmitters of which can transmit two different code signals, is known. A first receiver in the vehicle controls the central unlocking and locking of all the locks in the usual manner when the first code signal is received. A second receiver is provided in the vehicle which only activates the trunk lid without influencing the door locks when the second code signal is received. The locking of the trunk can then only be canceled after the second code signal is received again at the second receiver.
In addition, central locking systems are known with delayed forwarding of locking pulses (German Patent Documents DE 29 41 899 A1, DE 29 42 852 A1) which permit the vehicle user, after centrally locking his vehicle by means of the driver's door locking station, within a predetermined time period still to open at least the trunk lid before its delayed locking after the expiry of the aforesaid time period.
At this point, it should be noted that with an analogous application of such an embodiment to the present problem a conceivable solution could be provided which, however, remains unsatisfactory because after the expiry of the time period the user who has got into the car would also be locked in involuntarily. For example, it has been suggested in German Patent Document DE 36 12 306 A1 to provide a central locking system with a selection switch arranged in the passenger compartment of the vehicle, by means of which the usual central function of the central locking system can be canceled either only for unlocking or for unlocking and locking. It was also suggested in German Patent Document DE 38 30 511 C1 to provide a central locking system in which, by a single actuation of a locking station provided with a control switch, only the respective lock is unlocked in a purely mechanical way and a central unlocking of all the locks is only possible by means of the repeated actuation of the same closing point.
Finally, a central locking system with multiple station operation is also known (European Patent Document EP 0 245 001 A2), in which different selectable unlocking possibilities are offered (individual unlocking of a lock or central unlocking of all locks) by means of specific, different lock cylinder positions in the same direction. This system also provides that an additional key withdrawal position can be obtained, on a lock on the driver's door, by the key actuation of the lock cylinder in the locking direction. However, this position serves solely for switching on an additional mechanical anti-theft protection which prevents a central unlocking from another point. A key-secured position of a lock which prevents it being unlocked via the central locking system is not disclosed in the European Patent Document.
A known central locking system (German Patent Document DE 35 31 349 C1) mentioned earlier is controlled by bistable selection switches with two fixed contacts connected to different electrical potentials. It has a switching contact, connected via an individual control line to a central control circuit, at each closing point. The control line, one per locking station, always conducts a defined electrical potential and the central control circuit is activated by potential change pulses for the purpose of central unlocking or locking. In this system, a transition from zero potential to negative potential on a control line has no effect on the central control circuit.
Another known central locking system (German Patent Document DE 37 03 590 C1) has a central control circuit with only two control inputs, one for locking control signals, the other for unlocking control signals, to which as many locking or unlocking control switches as desired in the form of push-button switches can be connected via one busbar conductor in each case. These push-button switches are assigned in pairs also to the locking stations for the operation of the central locking system and are briefly actuated by pulses by correspondingly directed swivelling of the key in these locking stations.
An object of the invention is to provide a process for controlling a central locking system with which the above-mentioned inconvenience of "unavoidable central locking of all the locks when the lock of the trunk lid is locked by key" can be avoided in a simple way, and to provide a central locking system of the generic type with means by which the vehicle user does not have to unlock the door lock of the vehicle again after moving the locking station of the trunk lid or of the corresponding lock into the key-secured position if he subsequently wishes to get into the vehicle.
This and other objects are achieved by the present invention which provides a method for controlling a central locking system (CLS) for door locks and hinged lid locks of a motor vehicle that has multiple operation of the CLS from a first mechanical locking station on a trunk lid and at least one further mechanical locking station on a door. The multiple station operation is performed via a first electrical control switch assigned to the first locking station and at least a second electrical control switch which is assigned to the further locking station, each of the first and second electrical control switches being switchable via the assigned closing point for the generation of unlocking and locking control signals which bring about a corresponding activation of the CLS. The first locking station is movable into a key-secured position by actuation via a key in a locking direction starting from an unlocked position or a neutral key withdrawal position to cause the generation of a locking control signal of the first control switch, which is also actuated when the first closing point is moved into the key-secured position, from which key-secured position the associated lock can only be unlocked again by the key and not by the CLS, the actuation of the first locking station in the locking direction being directed, with respect to the neutral key withdrawal position, in the opposite direction to an actuation of the first locking station in the unlocking direction. The method includes triggering a switching operation at an electrical switch assigned to the first locking station when the first locking station is actuated by the key in the unlocking direction, and at least indirectly suppressing the effect of the locking control signal of the first control switch, which is also actuated when the first locking station is subsequently moved into the key-secured position, via a switching device cooperating with the electrical switch during the switching operation.
The objects of the invention are also achieved by the present invention which provides a central locking system (CLS) for motor vehicle door and trunk locks with multiple station operation, and comprises a locking station of a trunk lid and at least one additional locking station, each locking station having at least one control switch which can be switched via actuation by a key. The locking station of the trunk lid also has an associated lock and a closing cylinder movable via a key into a secured, locked position starting from a neutral key withdrawal position, in which secured, locked position the associated lock can only be unlocked by the key and not by the CLS. The system has a central control circuit, coupled to the locking station of the trunk lid and the additional locking station, which has inputs to which unlocking and locking control signals of the control switches are applied. The central control circuit at least indirectly activates lock actuators of the CLS in accordance with the locking and unlocking control signals. An electrical switch is provides that is coupled to the first locking station and which can be switched when the first locking station is actuated in the unlocking direction. There is also a switching device which can be activated at least indirectly by the electrical switch and which, after being activated, suppresses at least for a limited period the effect in the central control circuit of the locking control signal generated by the control switch of the locking station of the trunk lid.
With a central locking system modified according to the present invention, the vehicle user can avoid a central locking of the locks of his vehicle when locking the trunk lid by key in that he initially once more actuates the associated unlocked lock point or the closing cylinder with his key in the unlocking direction. A switching operation is then triggered or a switch is then actuated, and the locking station, preferably within a predetermined time period, is then moved in the usual manner into the position which is locked by mechanical or "secured" means.
By means of a detectable electrical switching signal of the actuated switch, a switching device can be activated which cancels or suppresses the effect on the central control circuit of the central locking system of the locking control signal, generated during locking, of the control switch assigned to the locking station of the trunk lid.
On the other hand, the switching operation of the switch can be utilized, even without the generation of a detectable electrical switching signal, for the desired suppression of the effect of the locking control signal if the switch is looped directly into the associated control line with its switching contact and is opened during the switching operation. The switch has to be then closed again at the latest when the key-secured position is reached, in order to restore the usual mode of operation of the central locking system.
With the present invention, all the normal functions of the central locking system are retained, in an advantageous manner, in their entirety. In particular, it is still possible to centrally unlock and to lock all the locks on the vehicle from the locking station of the trunk lid.
The process according to the invention can be carried out with both control principles.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.